Transport properties of CsHSO4 investigated by impedance spectroscopy and nuclear magnetic resonance

Abstract

Transport properties of the superprotonic conductor, CsHSO4, have been investigated by impedance spectroscopy and nuclear magnetic resonance (NMR). It has been found that both, conductivity (σ) and NMR diffusion (DNMR) are practically isotropic in the high-conductive (superprotonic) phase (above 414 K). The NMR diffusion coefficient, DNMR, increases rapidly and discontinuously at the melting point (~490 K). The temperature change of DNMR in the superprotonic phase is characterized by a smaller activation energy compared to that in the liquid state. The \(D_{\sigma } \) values calculated from the Nernst-Einstein relation practically coincide with DNMR in the superprotonic phase, i.e., the Haven ratio \(H_{{\text{R}}} = {D_{{{\text{NMR}}}} } \mathord{\left/ {\vphantom {{D_{{{\text{NMR}}}} } {D_{\sigma } }}} \right. \kern-\nulldelimiterspace} {D_{\sigma } }\) is close to unity. This indicates that in this phase the proton motion is rather uncorrelated.